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[boost.format] another compilation error with VC 2013
by Olaf Krzikalla 14 Feb '14

14 Feb '14

Hi boost, I've encountered another VC 2013 problem. alt_sstream doesn't compile, since its base class std::basic_streambuf has an explicitely nonthrowing dtor. I actually had to fix it at two places: - virtual ~basic_altstringbuf() + virtual ~basic_altstringbuf() BOOST_NOEXCEPT_OR_NOTHROW and + virtual ~basic_oaltstringstream() BOOST_NOEXCEPT_OR_NOTHROW + { } Please, can anyone explain the second place: why doesn't the compiler-generated dtor inherit the nothrow clause? Is it due to the other base class (base_from_member< shared_ptr<...> >)? The weird thing is that MS even advocates the usage of boost.format with MSVC 2013: http://msdn.microsoft.com/en-us/library/hh438469.aspx So I am not 100% sure, whether the problem is boost/MSVC-related or my configuration is wrong. Google is surprisingly quiet regarding the issue. Best Olaf

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Fwd: boost::unique_lock throw a exception
by shada 13 Feb '14

13 Feb '14

I use boost1.52 on windows2003sp2, boost::unique_lock throw a exception, please help me. stack is: *RaiseException_CxxThrowExceptionboost::throw_exception<boost::lock_error>[e:\library\boost_1_52\boost\throw_exception.hpp：67] boost::shared_mutex::timed_lock[e:\library\boost_1_52\boost\thread\win32\shared_mutex.hpp：430]boost::shared_mutex::lock[e:\library\boost_1_52\boost\thread\win32\shared_mutex.hpp：382]boost::unique_lock<boost::shared_mutex>::lock[e:\library\boost_1_52\boost\thread\locks.hpp：510]* ------------------------------------------------------------------------ *bool timed_lock(boost::system_time const& wait_until){ for(;;) { state_data old_state=state; for(;;) { state_data new_state=old_state; if(new_state.shared_count || new_state.exclusive) { ++new_state.exclusive_waiting; if(!new_state.exclusive_waiting) { boost::throw_exception(boost::lock_error()); } new_state.exclusive_waiting_blocked=true; } else { new_state.exclusive=true; }*

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Minimum perfect matching
by Paolo Bolzoni 13 Feb '14

13 Feb '14

Dear list, I am using boost graph and I need to solve a variant of the classic TSP. Boost providess a function (metric_tsp_approx) to get a Halmintonian cycle over a full connected metric weighted graph. However I need something slightly different. I need a path that visits all vertices starting and ending to two well known vertices (let be s and d). Seeking around, I found the suggestion of adding a node connected to s d and with the weight of the edge (s,d). The TSP solution of the new graph is the solution, just removing the new node. The problem is that now the graph is not complete anymore so the metric_tsp_approx's approach does not work anymore. Another possiblity is using a variant of Christofides algorithm, but one of the passages of that is the minimum weight perfect matching. I am a little confused by the documentation of the functions about Maximum Cardinality Matching(1), it is possible to use them to find the a maximum cardinality matching so that the total weight of all selected edges is minimal? Otherwise, is there an alternate approach to my problem? Yours faithfully, Paolo (1) http://www.boost.org/doc/libs/1_55_0/libs/graph/doc/maximum_matching.html

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Re: [Boost-users] intrusive data structures with custom pointer class
by Matei David 12 Feb '14

12 Feb '14

On Fri, 07 Feb 2014 16:00:31 -0500 boost-users-request(a)lists.boost.org wrote: > Message: 6 > Date: Fri, 07 Feb 2014 22:00:23 +0100 > From: Ion Gazta?aga <igaztanaga(a)gmail.com> > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] intrusive data structures with custom > pointer class > Message-ID: <52F54967.9020704(a)gmail.com> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > El 06/02/2014 23:52, Matei David escribi?: > > Hi, > > > > > > I would like to use some boost::intrusive data structures (lists and > > trees) in a project I'm working on, but I ran into trouble trying to > > customize the existing classes to my needs. I decided to post my > > problem here, in case somebody knowledgeable of boost::intrusive > > *implementation details* can assist me. Thank you in advance. > > Hi Meti, > > You have a lot of questions, I hope I can answer most of them. > > > Background: > > > > In the project I'm working on, I need to manage a large number of > > objects in memory. The data is dynamic, so I need to be able to > > alloc&dealloc objects, in addition to keeping the objects in various > > lists&trees (for which I'm trying to use boost::intrusive). The RAM > > usage is large (think, >100GB), but the number of objects is smaller > > than 2^32. So one thing I'd like to do is to replace 8-byte raw > > pointers with 4-byte offsets into a deque. Doing this would solve > > the alloc/dealloc part. However, I now need to customize > > boost::intrusive containers to work with these 4-byte offsets > > instead of raw pointers. > > I guess the deque is a global object, right. What do you mean with > "offset" into a deque? It's the offset passed to "deque::operator[]"? Hi and thanks for the reply. Contrary to some of the things you said, I found a way to (partly?) implement my specific use case with boost::intrusive. However, I have some concerns: - I only tested a small part of the boost::intrusive functionality with my customizations, so my success might be superficial. Could you have a look and make an informed guess as to how stable this is? - I am concerned that further boost updates might inadvertently break my customizations, and I would hate to list =1.55 as a specific dependency (as opposed to >=1.55). I understand this can never be fully avoided, but I'm hoping you could decide to support my use case, either officially by including it in the code base and the docs, or at least non-officially by being aware of it. I found and fixed this along the way: https://svn.boost.org/trac/boost/ticket/9650 Let me restate my specific use-case: I have several types A, B,..., and I want each object a1 of type A to be kept in a tree (say) along with other A objects (not all A objects go in the same tree). Since there are so many A objects, I care about their memory usage. Specifically, I want to replace 8-byte pointers (A*) by 4-byte handles (which I call Ptr<A>). An A-handle is really an uint32_t offset into the array of type A objects. A B-handle is also an offset, but into another array, holding B objects. Thus: - The transformation handle-to-object_address is O(1). - The transformation object_address-to-handle is prohibitive. - I can only use A-handles for A objects stored in a unique A-object array. If I construct an A object elsewhere, I can refer to it with a raw pointer, but not with an A-handle. - Objects of type B are stored in a different array than objects of type A. This means, in particular, that handles are not freely re-interpretable as real/smart pointers are with casts. So, dereferencing the A handle 42 gives me the A object number 42 from the A object array; but dereferencing the same handle reinterpreted as a B handle gives me the object number 42 from the B object array. NOTE: These pointer casts are my primary source of concern. I will come back to this below. My goal is to make boost::implicit structures work with these handles instead of raw/smart pointers. Intuition tells me there isn't a serious reason why they shouldn't, and that this type of scenario is general enough to be of interest to others, and therefore to boost maintainers. My (partial) success is here: https://github.com/mateidavid/sga/raw/matei-dev/src/Dev/factory.hpp https://github.com/mateidavid/sga/raw/matei-dev/src/Dev/test-i_list-orig.cpp https://github.com/mateidavid/sga/raw/matei-dev/src/Dev/test-i_tree-orig.cpp The code is a work in progress. You'll need a few more included files. I'm compiling with, e.g.: $ [g++|clang++] [-DNONSTATIC_VALUE_TRAITS] -I <path_to_1_55> -g -O0 -std=c++0x -pedantic -Wall -Wextra -o test-i_list-orig test-i_list-orig.cpp common.cpp globals.cpp For lists with nonstatic traits, you need the bug fix mentioned earlier. > > - Given a type T, I rolled out pointer-replacement class Ptr<T> > > which holds a 4-byte int, and upon operator*, it produces a Ref<T> > > object. > > - A reference-replacement Ref<T> class similarly holds a 4-byte int, > > it implements operator& which produces the associated Ptr<T> > > object, and it also provides an operator T& () conversion which > > dereferences the object from the deque. > > - With these, I tried a custom traits struct looking like this: > > value_type = node := T > > node_ptr = pointer := Ptr<T> > > reference := Ref<T> > > Boost.Intrusive models (or tries to model) a pointer type that can be > modeled with std::pointer_traits (more precisely > boost::intrusive::pointer_traits). In that model the reference type > must be a type that implements the dot operator. Sadly in C++ there > is no way to implement a class that overloads this operator. That's > why your pseudo-reference type will not work. I thought about this. There are 2 different perspectives. From the point of view of the boost::intrusive data structures (e.g., list), I think these structures should never ever dereference any object they store. So, e.g. inside list.hpp, if we have somewhere an object val of type "reference" (such as in insert()), the code should never use "o.<field> = 42". Instead, whatever fields the data structure needs to access (like r/w access to parent pointers), they should access them through the traits class methods (e.g. traits::set_field(o,42)). However, this already seems to be the case today. From the POV of the traits classes, indeed, these need to dereference values. First of all, there is a problem with the function signatures. In http://www.boost.org/doc/libs/1_55_0/doc/html/intrusive/value_traits.html the signature of to_node_ptr should be changed from: static node_ptr to_node_ptr (value_type &value) to: static node_ptr to_node_ptr (pointer_traits<pointer>::reference value) This just involves changing the docs; you can change the signature (as I did in my customization) and it compiles just fine. Also, even with the right signature, the function should never do: { return value.get_node_ptr(); } but instead: { return (&value)->get_node_ptr(); } because both reference::operator& and pointer::operator-> are overloadable. However, the concern about traits classes is not as serious as the one about the data structures because users are given the option to write their own traits classes anyhow. So overall, I think the problem with the dot operator isn't serious enough to make this use case unattainable. > > A. The traits classes seem to be there to support 2 existing > > customization types, namely the situation where "node" is a base > > class of "value" (implementing "base hooks") and the situation > > where "node" is a member of "value" (implementing "member hooks"). > > My situation represents a 3rd customization type. > > You can use function_hook, the hook does not need to be a member or > base class. The hack I used seems to work for now. In the future, I think it would be nice to have the option to explicitly specify the header node (so the container would just use a pointer) in the interest of clearly separating any type of node/value allocation from the containers. But I wouldn't say that's a priority. > > B. Even though the traits classes allow one to specify pointer > > types, it's possible (?) that under the hood the classes were > > designed to support only raw pointers and smart pointers, not the > > indirect offset-like pointers I need. > > See previous answer about supported reference types. > > > Given A&B, it seems to me that in my customization I would need 2 > > different hacks. In the interest of code stability, I started > > wondering whether it is feasible to adapt existing boost::intrusive > > data to my needs (my first instinct) as opposed to simply rolling > > out my own rbtree. > > I don't know the impact of supporting smart reference types. It might > be impossible, I haven't tried it. > > > 0. Obviously: Have you seen a similar situation being dealt with > > before? Maybe there's an existing solution out there. My reluctance > > to rolling out my own intrusive rbtrees is due to the fact I'd have > > to test them, as opposed to using a known implementation. > > > > 1. Are boost::intrusive data structures supposed to support custom > > pointer classes (neither real pointers nor smart pointers)? For > > instance, in 1.46 I found this code in > > boost/intrusive/detail/tree_algorithms.hpp > > Yes, boost::interprocess::offset_ptr (but a raw reference can be > converted to a smart pointer easily). > > > static node_ptr uncast(const_node_ptr ptr) > > { > > return node_ptr(const_cast<node*>( > > ::boost::intrusive::detail::boost_intrusive_get_pointer(ptr))); > > } > > However, intrusive lists worked just fine in 1.46, which suggests > > this was simply a bug. > > This was fixed in recent Boost releases using pointer_traits to > implement this function. You can customize pointer_traits to > implement your own version. > > > 2. Can you point me to an example of defining and using custom > > pointer class with boost::intrusive? To enable compilation (of > > lists only) in 1.46, I had to customize std::iterator_traits (that > > part I understood), but then also boost::pointer_to_other and > > boost::intrusive::detail::smart_ptr_type. Even though the code > > compiled, I don't know what those are doing exactly, so I'm weary of > > them. > > See the example in libs/intrusive/example/doc_offset_ptr.cpp and > boost/interprocess/offset_ptr.hpp. See the most recent boost version > for fixed bugs. A dumb smart pointer is used in boost intrusive > tests, and it's found in libs/intrusive/test/smart_ptr.hpp, but it's > a bit oudated. Anyway I think pointer requirements for > Boost.Intrusive might no be correctly specified and it might require > some fixes. Recent versions uses pointer_traits, and I recommend you > this approach. > > > 3. In 1.55, I have a few more pages of errors, I think mainly due to > > these pointer customization issues I don't fully understand. > > Something seems to have changed from 1.46 to 1.55. Is there a > > reference about what changed? Or is there a portable way of rolling > > out such a custom pointer class? > > pointer_traits was specified and all code was ported to use this > customization point. The reference type is assumed to be a raw > reference (as there is no way to overload operator dot to implement a > working smart reference). > > The only why to use Boost.Intrusive would be to implement a smart > pointer (of any pointee type) that can be fastly obtained from raw > reference. If this is your case, Boost.Intrusive might already have > all that you need. If you need a "smart reference", then > Boost.Intrusive is not prepared for this and I don't know how many > effort would require adding support for this (even if this approach > is feasible). > > The problem with "node" objects embedded in the container could be > solved with an option that allows external allocation of these nodes. > > Best, > > Ion Empirically, since I got the containers (at least partially) working with non-standard references, they must be already prepared to handle those. Theoretically, as I described above, the containers themselves should never have to dereference specific fields anyhow, and therefore should be immune to reference type changes. The more serious concern, ***and the reason I wrote all this***, is with pointer casts. Unlike raw or smart pointers, these handles are type-specific. So casting them to something else and then dereferencing that object should be done with care. Take bstree, for instance. Its base class (bstbase3) inherits from node & Value_Traits. The way you obtain access to the Value_Traits struct (used with stateful traits) is through a pointer which you later want to dereference: typedef typename pointer_traits<node_ptr>::template rebind_pointer<const real_value_traits>::type const_real_value_traits_ptr; const_real_value_traits_ptr real_value_traits_ptr() const { return pointer_traits<const_real_value_traits_ptr>::pointer_to( this->get_real_value_traits()); } With handles, the only way I see for this to work is to eventually transform handles into real pointers. So, Ptr<T>::rebind<U>::type should be U* except for U in {T, const T} and possibly {void, const void}. I initially tried to wrap voids as well, but I get errors. (Try adding -DWRAP_VOID when compiling test-i_list-orig.cpp) The problem are these casts: - In iiterator_members: const_void_pointer := pointer_traits<NodePtr>::rebind_pointer<const void> - In iiterator: void_pointer := pointer_traits<node_ptr>::rebind_pointer<void> - In list_iterator: const_real_value_traits_ptr := pointer_traits<void_pointer>::rebind_pointer<const real_value_traits> - iiterator_members ctor takes as 2nd argument a const_void_pointer - list_iterator ctor calls iiterator_members ctor, passing as 2nd arg a const_real_value_traits_ptr When I wrap voids: const_void_pointer := Ptr<const void> void_pointer := Ptr<const void> const_real_value_traits_ptr := value_traits* which means the container code is trying to cast: Ptr<T> -> value_traits* -> Ptr<const void> -> value_traits* -> deref, and the 2nd cast fails. However, things seemed to work ok if I don't wrap voids. So the main concern with my use case is that: ***intrusive containers should not cast node_ptr objects into other types of pointers (not even void*), and then attempt to cast them back***. They can cast other pointers (such as value_traits*) to void* and back, but not node_ptr-s. Please have this use case in mind when further developing boost::intrusive. The files I linked above can serve as a basic test case. I can help writing up this use case in slightly more detail if you think that would be useful for others. Thanks, Matei

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[boost.tr1] compilation errors with VC 2013
by Olaf Krzikalla 12 Feb '14

12 Feb '14

Hi, I have encountered plenty of compilation errors with VC 2013 caused by including <boost/tr1/memory.hpp> or <boost/tr1/functional.hpp>. The errors happen with all versions tried (1.40, 1.53 and 1.55). Is boost.tr1 deprecated for newer compilers? Best Olaf

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Compilation problem with has_binary_operator.hpp on Mac OSX
by Tim Burgess 12 Feb '14

12 Feb '14

Hi, I'm building a framework project using Xcode 4.6 configured to use the Apple GCC 4.2 compiler (my project also uses wxWidgets, so this compiler is required). Using Boost 1.55.0 I get: cd /Users/tim/Developer/RBSpeech setenv LANG en_US.US-ASCII /Applications/Xcode.app/Contents/Developer/usr/bin/llvm-gcc-4.2 -x objective-c++ -arch x86_64 -fmessage-length=0 -pipe -Wno-trigraphs -fpascal-strings -O0 -Wreturn-type -Wunused-variable -Wuninitialized -Wshorten-64-to-32 -DDEBUG=1 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Develop er/SDKs/MacOSX10.8.sdk -fasm-blocks -mmacosx-version-min=10.6 -gdwarf-2 -fvisibility-inlines-hidden -iquote /Users/tim/Library/Developer/Xcode/DerivedData/RBSpeech-gglcnsigefizlfbidkwh bsxvlwng/Build/Intermediates/RBSpeech.build/Debug/RBSpeech.build/RBSpeech-ge nerated-files.hmap -I/Users/tim/Library/Developer/Xcode/DerivedData/RBSpeech-gglcnsigefizlfbidk whbsxvlwng/Build/Intermediates/RBSpeech.build/Debug/RBSpeech.build/RBSpeech- own-target-headers.hmap -I/Users/tim/Library/Developer/Xcode/DerivedData/RBSpeech-gglcnsigefizlfbidk whbsxvlwng/Build/Intermediates/RBSpeech.build/Debug/RBSpeech.build/RBSpeech- all-target-headers.hmap -iquote /Users/tim/Library/Developer/Xcode/DerivedData/RBSpeech-gglcnsigefizlfbidkwh bsxvlwng/Build/Intermediates/RBSpeech.build/Debug/RBSpeech.build/RBSpeech-pr oject-headers.hmap -I/Users/tim/Library/Developer/Xcode/DerivedData/RBSpeech-gglcnsigefizlfbidk whbsxvlwng/Build/Products/Debug/include -I/users/tim/developer/libraries/wxwidgets/include -I/users/tim/developer/libraries/cryptopp -I/users/tim/developer/libraries/boost_1_55_0 -I/users/tim/developer/sources/surfacereader -I/Users/tim/Library/Developer/Xcode/DerivedData/RBSpeech-gglcnsigefizlfbidk whbsxvlwng/Build/Intermediates/RBSpeech.build/Debug/RBSpeech.build/DerivedSo urces/x86_64 -I/Users/tim/Library/Developer/Xcode/DerivedData/RBSpeech-gglcnsigefizlfbidk whbsxvlwng/Build/Intermediates/RBSpeech.build/Debug/RBSpeech.build/DerivedSo urces -F/Users/tim/Library/Developer/Xcode/DerivedData/RBSpeech-gglcnsigefizlfbidk whbsxvlwng/Build/Products/Debug -I/Users/tim/developer/libraries/wxwidgets/build-debug/lib/wx/include/osx_co coa-unicode-static-2.9 -I/Users/tim/developer/libraries/wxwidgets/include -D_FILE_OFFSET_BITS=64 -D__WXMAC__ -D__WXOSX__ -D__WXOSX_COCOA__ -include /Users/tim/Library/Developer/Xcode/DerivedData/RBSpeech-gglcnsigefizlfbidkwh bsxvlwng/Build/Intermediates/PrecompiledHeaders/RBSpeech-Prefix-filshqejewqv wmcnuphmjzrmapcf/RBSpeech-Prefix.pch -c /Users/tim/Developer/RBSpeech/../Sources/SurfaceReader/RBSpeech.mm -o /Users/tim/Library/Developer/Xcode/DerivedData/RBSpeech-gglcnsigefizlfbidkwh bsxvlwng/Build/Intermediates/RBSpeech.build/Debug/RBSpeech.build/Objects-nor mal/x86_64/RBSpeech.o cc1objplus: warning: -Wuninitialized is not supported without -O In file included from /users/tim/developer/libraries/boost_1_55_0/boost/type_traits/has_left_shift .hpp:43, from /users/tim/developer/libraries/boost_1_55_0/boost/lexical_cast.hpp:165, from /Users/tim/Developer/RBSpeech/../Sources/SurfaceReader/RBStringFuncs.hpp:11, from /Users/tim/Developer/RBSpeech/../Sources/SurfaceReader/RBSpeech.h:27, from /Users/tim/Developer/RBSpeech/../Sources/SurfaceReader/RBSpeech.mm:4: /users/tim/developer/libraries/boost_1_55_0/boost/type_traits/detail/has_bin ary_operator.hpp:155: error: expected unqualified-id before 'do' The project uses OSX10.8 as its base SDK, but has OSX10.6 as its deployment target to provide backward compatibility and I made sure that my Boost libraries specified the 10.6 SDK as a minimum. Can anybody advise, please? Best wishes. Tim Burgess

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[property_tree] Compilation Problem when #including <boost/property_tree/json_parser.hpp>
by Adi Shavit 12 Feb '14

12 Feb '14

Hi, On VS2010, the following code does not compile if I restore the commented out #include: *// #include <boost/property_tree/json_parser.hpp>* struct X { enum Labels { ERROR, ONE, TWO, THREE }; // problem => ^^^^^ }; void f() { X::Labels r = X::ERROR; // problem => ^^^^^ } The VS2010 errors are: t.cpp(5): error C2059: syntax error : 'constant' t.cpp(5): error C2143: syntax error : missing ';' before '}' t.cpp(5): error C2238: unexpected token(s) preceding ';' t.cpp(7): error C2059: syntax error : '}' t.cpp(7): error C2143: syntax error : missing ';' before '}' t.cpp(7): error C2059: syntax error : '}' t.cpp(11): error C2589: 'constant' : illegal token on right side of '::' t.cpp(11): error C2059: syntax error : '::' It seems that somewhere inside the #include hierarchy the symbol ERROR is #defined to cause this code to fail. Renaming ERROR to something else avoids this problem. I think I tracked it into ' boost/spirit/home/classic/iterator/impl/file_iterator.ipp' but I'm not sure where exactly it is coming from. Adi

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compilation error while using intel c++ XE 14.0
by Bo Chen 12 Feb '14

12 Feb '14

Hi, While I compile the code(see attached) based on the boost 1.54/1.55 using intel compiler c++ XE 14.0, I got following error. Could you help please? Thanks. Chen Bo 1>------ Build started: Project: intelTest, Configuration: Debug Win32 ------ 1>Build started 07/02/2014 18:09:33. 1>ClCompile: 1> ***** ClCompile (Win32 - Intel C++) 1> intelTest.cpp 1> Warning #672: the command line options do not match those used when precompiled header file "Debug\intelTest.pchi" was created 1> 1>c:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\xutility(2215): error : no instance of overloaded function "std::_Copy_impl" matches the argument list 1> argument types are: (boost::detail::multi_array::array_iterator<int, const int *, boost::mpl::size_t<3U>, boost::detail::multi_array::const_sub_array<int, 2U, const int *>, boost::random_access_traversal_tag>, boost::detail::multi_array::array_iterator<int, const int *, boost::mpl::size_t<3U>, boost::detail::multi_array::const_sub_array<int, 2U, const int *>, boost::random_access_traversal_tag>, boost::detail::multi_array::array_iterator<int, int *, boost::mpl::size_t<3U>, 1> boost::detail::multi_array::sub_array<int, 2U>, boost::random_access_traversal_tag>, boost::detail::iterator_category_with_traversal<std::input_iterator_tag, boost::random_access_traversal_tag>, boost::detail::iterator_category_with_traversal<std::input_iterator_tag, boost::random_access_traversal_tag>) 1> return (_Copy_impl(_First, _Last, 1> ^ 1> detected during: 1> instantiation of "_OutIt std::_Copy_impl(_InIt, _InIt, _OutIt, std::tr1::false_type) [with _InIt=boost::detail::multi_array::array_iterator<int, const int *, boost::mpl::size_t<3U>, boost::detail::multi_array::const_sub_array<int, 2U, const int *>, boost::random_access_traversal_tag>, _OutIt=boost::detail::multi_array::array_iterator<int, int *, boost::mpl::size_t<3U>, boost::detail::multi_array::sub_array<int, 2U>, boost::random_access_traversal_tag>]" at line 2227 1> instantiation of "_OutIt std::copy(_InIt, _InIt, _OutIt) [with _InIt=boost::detail::multi_array::array_iterator<int, const int *, boost::mpl::size_t<3U>, boost::detail::multi_array::const_sub_array<int, 2U, const int *>, boost::random_access_traversal_tag>, _OutIt=boost::detail::multi_array::array_iterator<int, int *, boost::mpl::size_t<3U>, boost::detail::multi_array::sub_array<int, 2U>, boost::random_access_traversal_tag>]" at line 322 of 1> "C:\Users\chbeb9\Downloads\boost_1_55_0\boost/multi_array/view.hpp" 1> instantiation of "boost::detail::multi_array::multi_array_view<T, NumDims> &boost::detail::multi_array::multi_array_view<T, NumDims>::operator=(const boost::detail::multi_array::multi_array_view<T, NumDims> &) [with T=int, NumDims=3U]" at line 447 of "C:\Users\chbeb9\Downloads\boost_1_55_0\boost/multi_array.hpp" 1> instantiation of "boost::multi_array<T, NumDims, Allocator> &boost::multi_array<T, NumDims, Allocator>::resize(const boost::detail::multi_array::extent_gen<NumDims> &) [with T=int, NumDims=3U, Allocator=std::allocator<int>]" at line 32 of "intelTest.cpp" 1> 1> compilation aborted for intelTest.cpp (code 2)

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Boost::preprocess __VAR_ARGS__ compile fail
by garthh 12 Feb '14

12 Feb '14

This simple piece of code doesn't compile for me in boost 1.54 on MacOSX: #include <boost/preprocessor.hpp> #define debugprintf(...) \ printf(BOOST_PP_SEQ_ELEM(0, BOOST_PP_VARIADIC_TO_SEQ(__VA_ARGS__))) main () { debugprintf("test"); } I've spent ages on it without success. Any suggestions would be greatly appreciated! Compile output: error: too few arguments provided to function-like macro invocation debugprintf("boost test"); ^ main.cpp:15:17: note: expanded from macro 'debugprintf' fprintf(stderr, BOOST_PP_SEQ_ELEM(0, BOOST_PP_VARIADIC_TO_SEQ(__VA_ARGS__))); \ ^ /usr/local/Boost/1.54/include/boost/preprocessor/seq/elem.hpp:22:39: note: expanded from macro 'BOOST_PP_SEQ_ELEM' # define BOOST_PP_SEQ_ELEM(i, seq) BOOST_PP_SEQ_ELEM_I(i, seq) ^ /usr/local/Boost/1.54/include/boost/preprocessor/seq/elem.hpp:41:45: note: expanded from macro 'BOOST_PP_SEQ_ELEM_I' # define BOOST_PP_SEQ_ELEM_I(i, seq) BOOST_PP_SEQ_ELEM_II(BOOST_PP_SEQ_ELEM_ ## i seq) ^ /usr/local/Boost/1.54/include/boost/preprocessor/seq/elem.hpp:43:62: note: expanded from macro 'BOOST_PP_SEQ_ELEM_II' # define BOOST_PP_SEQ_ELEM_II(im) BOOST_PP_SEQ_ELEM_III(im) ^ main.cpp:21:2: error: use of undeclared identifier 'BOOST_PP_SEQ_ELEM_III' debugprintf("boost test"); -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-preprocess-VAR-ARGS-compile-fail-t… Sent from the Boost - Users mailing list archive at Nabble.com.

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unable to use find() function in boost::associative property maps.
by Aniket Pugaonkar 12 Feb '14

12 Feb '14

Hi, The current boost::associative_property_map interface in boost::property_map does not provide a *find()* function interface from where we can find a key type from associative map. Although the associative property map concept was mainly developed for using boost::get and boost::put function efficiently on unique associative containers (such as std::map), it still does not have any interface for using find() function for searching whether an element exists in a map, My problem is explained below: I have a map, and I define a associative property map on it. as follows: std::map< int, int > *mymap*; boost::associative_property_map< std::map< int, int > > *my_asso_map* ( mymap ); I have a template function, named " exists_in " which checks whether a particular key_value, is present in the map or not. The function is as follows: *template* <typename map_t, typename key_t> bool *exists_in*(map_t map, key_t key) { return map.*find*(key) != map.end(); } ======================================== If I call this template function on mymap, it gives me no error: if( !exists_in ( mymap, key ) ----> no error Now, if I call template function on my_asso_map, it throws an error : if( !exists_in( my_asso_map, key ) ---->> error error: âclass boost::associative_property_map<std::map<int, int > >â has no member named âendâ error: âclass boost::associative_property_map<std::map<int, int > >â has no member named âfindâ I understand, my_asso_map just stores the address of mymap and provides get and put efficiently. But there are instances, where I have to *search* a key in my map. ( for example, if else loop as provided above ). I want to hide *mymap *and just expose *my_asso_map* to the user and everywhere I want to pass my_asso_map.. I am able to do this except for the *find*() function, because of which I had to keep passing my original *mymap *to the function/ functor and then use exists_in template function. Is there any way to implement a find() utility for associative property maps ? If find() interface can be added in library, that would be simply great ! Thanks, -- Thanks and regards, Aniket Pugaonkar

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